Unlike ceviche, aguachile isn't marinated for hours — raw shrimp is dressed in lime and chile water just minutes before eating, so it stays nearly raw and translucent rather than 'cooking' in the acid.
Raw shrimp is butterflied and quickly bathed in a blended sauce of lime juice, chile, and water, then topped with sliced cucumber, red onion, and a hit of extra chile. Seafood carts (marisquerías) along Sinaloa's coast, especially in Mazatlán, serve it ice-cold in tostada form.